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An end effector is provided and includes an outer tube, a coil member, a
plurality of fasteners, and an engagement member. The outer tube defines
a viewing window and a lockout window. The coil member is disposed within
the outer tube. The plurality of fasteners are disposed in the coil
member. The engagement member is disposed proximal to the plurality of
fasteners and is visible through the viewing window of the outer tube.
The engagement member is configured to translate proximal to the
plurality of fasteners to provide a count of the plurality of fasteners
remaining in the end effector.

1. An end effector comprising: an outer tube defining a viewing window
and a lockout window, the outer tube defining a first passageway
therethrough; a coil member disposed within the first passageway of the
outer tube, the coil member defining a second passageway therethrough; a
plurality of fasteners disposed in the second passageway of the coil
member, the plurality of fasteners configured to translate along the
second passageway; and an engagement member disposed proximal to the
plurality of fasteners and at least partially visible through the viewing
window of the outer tube, the engagement member configured to translate
along the second passageway proximal to the plurality of fasteners to
provide a count relative to the viewing window of the plurality of
fasteners remaining in the end effector, the engagement member including:
a body portion; and a biasing portion extending from the body portion,
the biasing portion having a biasing arm, the biasing arm biased
resiliently outward such that engagement of a free end of the biasing
portion of the engagement member with the lockout window restricts
further translation of the engagement member.

2. The end effector according to claim 1, wherein the outer tube includes
indicia disposed along the viewing window to indicate the count of the
plurality of fasteners remaining in the end effector.

3. The end effector according to claim 1, wherein the biasing arm of the
engagement member includes a first biasing arm and a second biasing arm
and wherein the outer tube includes a pair of lockout windows configured
to engage with the first and second biasing arms of the engagement
member.

4. The end effector according to claim 3, further including an inner tube
rotatably supported in the second passageway of the coil member, the
inner tube defining a third passageway, the inner tube having: a first
tine; and a second tine, wherein the first and second tines are radially
opposed and define a first channel and a second channel therebetween.

5. The end effector according to claim 4, wherein the plurality of
fasteners are disposed in the third passageway of the inner tube, the
plurality of fasteners each including a pair of opposed threaded
portions, the threaded portions of the plurality of fasteners being
configured to extend radially beyond the first channel and the second
channel of the inner tube respectively.

6. The end effector according to claim 5, wherein the threaded portions
of the plurality of fasteners are configured to engage a plurality of
successive winds of coil of the coil member.

7. The end effector according to claim 3, wherein the engagement member
includes a body and a pair of a threaded portions protruding radially
from the body thereof.

8. The end effector according to claim 7, wherein the first and second
biasing arms are approximated radially-inward toward the body of the
engagement member in a first configuration of the engagement member.

9. The end effector according to claim 7, wherein the first and second
biasing arms are disposed radially-outward with respect to the body of
the engagement member in a second configuration of the engagement member,
when the free end of the biasing arm is in registration with the lockout
window.

10. The end effector according to claim 3, wherein a width of a head
portion of each of the first and second biasing arms is greater than a
width of the viewing window such that the head portions of the first and
second biasing arms do not engage the viewing window during actuation of
the end effector.

11. The end effector according to claim 3, wherein a thickness of a head
portion of each of the first and second biasing arms is smaller than a
width of each lockout window such that the head portions of the first and
second biasing arms engage respective lockout windows, when the head
portions of the first and second biasing arms are in registration with
the respective lockout windows.

12. The end effector according to claim 11, wherein when the head
portions of the first and second biasing arms of the engagement member
engage the respective lockout windows, and when the threaded portions of
the body of the engagement member engage the inner tube, the inner tube
is unable to rotate relative to the outer tube.

13. An end effector comprising: an outer tube defining a viewing window
and a lockout window, the outer tube defining a first passageway
therethrough; a coil member disposed within the first passageway of the
outer tube, the coil member defining a second passageway therethrough; an
inner tube rotatably supported in the second passageway of the coil
member, the inner tube defining a third passageway, the inner tube
including: a first tine; and a second tine, wherein the first and second
tines are radially opposed and define a first channel and a second
channel therebetween; a plurality of fasteners disposed within the third
passageway of the inner tube, the plurality of fasteners configured to
translate along the third passageway; and an engagement member disposed
proximal to the plurality of fasteners and visible through the viewing
window of the outer tube, the engagement member configured to translate
along the third passageway proximal to the plurality of fasteners to
provide a count of the plurality of fasteners remaining in the third
passageway, the engagement member including: a body portion; and a
biasing portion extending from the body portion, the biasing portion
having a first biasing arm and a second biasing arm, the first and second
biasing arms biased resiliently outward such that engagement of a free
end of the biasing portion of the engagement member with the lockout
window restricts further translation of the engagement member.

14. The end effector according to claim 13, wherein the outer tube
includes indicia disposed along the viewing window to indicate the count
of the plurality of fasteners remaining in the end effector.

15. The end effector according to claim 13, wherein the plurality of
fasteners each include pair of opposed threaded portions, the threaded
portions of the plurality of fasteners being configured to extend
radially beyond the first channel and the second channel of the inner
tube respectively.

16. The end effector according to claim 15, wherein the outer tube
includes a pair of opposing lockout windows configured to engage with the
first and second biasing arms of the engagement member.

17. The end effector according to claim 16, wherein each of the first and
second biasing arms includes a head portion.

18. The end effector according to claim 16, wherein the opposing lockout
windows are located on the outer tube such that when a last fastener of
the plurality of fasteners is fired, the first and second biasing arms of
the engagement member are in registration with the respective lockout
windows.

19. The end effector according to claim 17, wherein when the head
portions of the first and second biasing arms of the engagement member
engage the respective lockout windows, and when the threaded portions of
the body of the engagement member engage the inner tube, the inner tube
is unable to rotate relative to the outer tube.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S.
Provisional Patent Application No. 62/258,102 filed Nov. 20, 2015, the
entire disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present disclosure relates to surgical fastener appliers, and
more particularly, to surgical tack appliers having surgical fasteners
including engagement members and associated methods of applying.

[0004] 2. Description of Related Art

[0005] In hernias, such as direct or indirect inguinal hernias, a part of
the intestine protrudes through a defect in the support abdominal wall to
form a hernial sac. The defect may be repaired using an open surgery
procedure in which a relatively large incision is made and the hernia is
closed off outside the abdominal wall by suturing. The mesh is attached
with sutures over the opening to provide reinforcement.

[0006] In contrast, minimally invasive, e.g., endoscopic or laparoscopic,
surgical procedures are currently available to repair a hernia. In
laparoscopic procedures, surgery is performed in the abdomen through a
small incision while in endoscopic procedures, surgery is performed
through narrow endoscopic tubes or cannulas inserted through small
incisions in the body.

[0007] Currently, minimally invasive surgical techniques for hernia repair
utilize surgical fasteners, e.g., surgical tacks, staples, and clips, to
secure the mesh to the tissue to provide reinforcement to the repair and
structure for encouraging tissue ingrowth. Surgical fasteners may be
deployed with a surgical fastener applier through a mesh and into tissue
below.

[0008] Challenges may be presented in affixing a mesh over a hernial
defect with surgical fasteners, e.g., in instances involving irregular or
uneven surface geometries, or in situations when internal body structures
are subject to movement and shifting. However, it is desirable to
minimize the number and size of surgical fasteners deployed through a
mesh to minimize trauma to the tissue below. Accordingly, it would be
desirable to provide a surgical fastener that is configured with
optimized mesh retention properties, while minimizing the portion or size
of the surgical fastener inserted into tissue.

[0009] Further, it would also be desirable to provide a means of counting
the surgical fasteners remaining in the surgical fastener applier as
surgeons may put down the surgical fastener applier when surgical
fasteners remain, pick up the surgical fastener applier for later use
during the procedure, and forget the number of surgical fasteners that
still remain in the surgical fastener applier.

SUMMARY OF THE INVENTION

[0010] According to an aspect of the present disclosure, an end effector
is provided and includes an outer tube, a coil member, a plurality of
fasteners, and an engagement member. The outer tube defines a viewing
window and a lockout window. The outer tube also defines a first
passageway therethrough. The coil member is disposed within the first
passageway of the outer tube, the coil member defining a second
passageway therethrough. The plurality of fasteners are disposed in the
second passageway of the coil member, the plurality of fasteners are
configured to translate along the second passageway. The engagement
member is disposed proximal to the plurality of fasteners and is visible
through the viewing window of the outer tube, the engagement member is
configured to translate along the second passageway proximal to the
plurality of fasteners to provide a count relative to the viewing window
of the plurality of fasteners remaining in the end effector. The
engagement member includes a body portion and a biasing portion extending
from the body portion. The biasing portion includes a biasing arm, the
biasing arm biased resiliently outward such that engagement of a free end
of the biasing portion of the engagement member with the lockout window
restricts further translation of the engagement member.

[0011] The outer tube may include indicia disposed along the viewing
window to indicate the count of the plurality of fasteners remaining in
the end effector.

[0012] The outer tube may include the biasing arm of the engagement member
to include a first biasing arm and a second biasing arm and a pair of
lockout windows configured to engage with the first and second biasing
arms of the engagement member.

[0013] The end effector may further include an inner tube rotatably
supported in the second passageway of the coil member, the inner tube
defining a third passageway. The inner tube may include a first tine and
a second tine, wherein the first and second tines are radially opposed
and define a first channel and a second channel therebetween.

[0014] The plurality of fasteners may be disposed in the third passageway
of the inner tube. The plurality of fasteners may each include a pair of
opposed threaded portions. The threaded portions of the plurality of
fasteners may be configured to extend radially beyond the first channel
and the second channel of the inner tube respectively.

[0015] The threaded portions of the plurality of fasteners may be
configured to engage a plurality of successive winds of coil of the coil
member.

[0016] The engagement member may include a body and a pair of a threaded
portions protruding radially from the body thereof

[0017] The first and second biasing arms may be approximated
radially-inward toward the body of the engagement member in a first
configuration of the engagement member.

[0018] The first and second biasing arms may be disposed radially-outward
with respect to the body of the engagement member in a second
configuration of the engagement member, when the free end of the biasing
arm is in registration with the lockout window.

[0019] A width of a head portion of each of the first and second biasing
arms may be greater than a width of the viewing window such that the head
portions of the first and second biasing arms do not engage the viewing
window during actuation of the end effector.

[0020] A thickness of a head portion of each of the first and second
biasing arms may be smaller than a width of each lockout window such that
the head portions of the first and second biasing arms engage respective
lockout windows, when the head portions of the first and second biasing
arms are in registration with the respective lockout windows.

[0021] In use, when the head portions of the first and second biasing arms
of the engagement member engage the respective lockout windows, and when
the threaded portions of the body of the engagement member engage the
inner tube, the inner tube may be unable to rotate relative to the outer
tube.

[0022] According to another aspect of the present disclosure, an end
effector is provided and includes an outer tube, a coil member, an inner
tube, a plurality of fasteners, and an engagement member. The outer tube
defines a viewing window and a lockout window. The outer tube also
defines a first passageway therethrough. The coil member is disposed
within the first passageway of the outer tube, the coil member defining a
second passageway therethrough. The inner tube is rotatably supported in
the second passageway of the coil member and defines a third passageway.
The inner tube includes a first tine and a second tine, wherein the first
and second tines are radially opposed and define a first channel and a
second channel therebetween. The plurality of fasteners are disposed in
the third passageway of the inner tube, the plurality of fasteners are
configured to translate along the third passageway.

[0023] The engagement member is disposed proximal to the plurality of
fasteners and is visible through the viewing window of the outer tube,
the engagement member is configured to translate along the third
passageway proximal to the plurality of fasteners to provide a count of
the plurality of fasteners remaining in the end effector. The engagement
member includes a body portion and a biasing portion extending from the
body portion. The biasing portion includes a first biasing arm and a
second biasing arm, the first and second biasing arms biased resiliently
outward such that engagement of a free end of the biasing portion of the
engagement member with the lockout window restricts further translation
of the engagement member.

[0024] The outer tube may include a pair of opposing lockout windows
configured to engage with the first and second biasing arms of the
engagement member.

[0025] The opposing lockout windows may be located on the outer tube such
that when a last fastener of the plurality of fasteners is fired, the
first and second biasing arms of the engagement member are in
registration with the respective lockout windows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the present disclosure will be appreciated by
reference to the drawings, wherein:

[0027] FIG. 1A is a side, perspective view of a tack applier according to
the present disclosure;

[0028] FIG. 1B is an enlarged view of the indicated area of detail of FIG.
1A;

[0029] FIG. 2A is a side, perspective view of an end effector according to
the present disclosure with an outer tube thereof separated therefrom;

[0030] FIG. 2B is a side, perspective view of an inner tube and a coil
member of the end effector of FIG. 2A;

[0031] FIG. 3, is a side, phantom perspective view of another embodiment
of an end effector according to the present disclosure;

[0032] FIG. 4 is a side, plan view of a fastener according to the present
disclosure;

[0033] FIGS. 5A-5B are perspective views of an engagement member shown in
a second configuration, according to the present disclosure;

[0034] FIG. 6 is a rear, plan view of the engagement member of FIGS. 5A-5B
shown in in a first configuration, according to the present disclosure;

[0035] FIG. 7A is a side, perspective view of a distal portion of the end
effector, shown in a locked out configuration;

[0036] FIG. 7B is a top, view of the distal portion of the end effector,
shown in the locked out configuration; and

[0037] FIG. 8 is a top plan view of the fastener deployed into a mesh and
tissue according to the present disclosure.

DETAILED DESCRIPTION

[0038] With reference now to the drawings wherein like numerals represent
like elements throughout the several views, the presently-disclosed
surgical fastener will be described. As used herein, the term "operator"
may refer to any user, e.g., a nurse, doctor, or clinician, of the
presently-disclosed surgical fastener. Further, the term "distal" refers
to that portion of the surgical fastener, or component thereof, further
from the operator while the term "proximal" refers to that portion of the
surgical fastener, or component thereof, closer to the operator.

[0039] Referring initially to FIG. 1A, an endoscopic surgical device, in
the form of an endoscopic surgical tack applier or tacker, is shown
generally as 100. Tack applier 100 includes a handle assembly 110, and an
endoscopic assembly 130 extending from handle assembly 110

[0040] Continuing with FIG. 1A, handle assembly 110 includes a handle
housing 112 formed from a first half-section 112a and a second half
section 112b joined to one another. First half-section 112a and second
half section 112b of handle housing 112 may be joined to one another
using know methods by those of skill in the art, including and not
limited to welding, fasteners (i.e., screws) and the like. Handle
assembly 110 also includes a trigger 114 pivotably connected to handle
housing 112, at a location remote from endoscopic assembly 130.

[0041] Handle assembly 110 includes a load/release slider 144 slidably
supported on handle housing 112 and being configured to effectuate a
loading/retention and a release/removal of an end effector 200, in the
form of a single use loading unit (SULU) or disposable loading unit
(DLU), as will be discussed in greater detail below. As shown in FIG. 1A,
end effector 200 is releasably connected to endoscopic assembly 130 and
is configured to store and selectively release or fire a plurality of
fasteners 10 (FIG. 4) therefrom and into mesh "M" overlying tissue "T"
(FIG. 8).

[0042] Turning now to FIGS. 1B, 2A, 2B, and 3, end effector 200 as briefly
described above, is shown. End effector 200 includes an outer tube 202
having an outer surface 202a and an inner surface 202b. Outer surface
202a defines a viewing window 204, extending longitudinally along a
length "L" of end effector 200. Inner surface 202b of outer tube 202
defines a first passageway 206, extending longitudinally along length "L"
of end effector 200. Viewing window 204 is configured such that an
engagement member 300, as will be discussed in greater detail below, can
be located within end effector 200 by a user. It is contemplated that a
user can use the location of the engagement member 300 with respect to
the viewing window 204 to keep count of the number of fasteners 10 left
in end effector 200. To this end, viewing window 204 includes indicia,
such as, for example, a plurality of graduated cutouts 204a corresponding
with the number of fasteners 10 loaded in end effector 200. The position
of engagement member 300 with respect to the plurality of graduated
cutouts 204a will inform a user of the number of fasteners 10 left in end
effector 200.

[0043] In one embodiment, as shown in FIG. 3, the indicia may also be a
plurality of numbers 204b to achieve the same purpose. Outer surface 202a
also defines a pair of opposing lockout windows 210a, 210b extending
through outer tube 202 (FIG. 7B). As will be discussed in greater detail
below, engagement member 300 is configured to engage the opposing lockout
windows 210a, 210b such that, upon engagement, further actuation of end
effector 200 is mechanically prevented.

[0044] As shown in FIGS. 2A and 2B, end effector 200 includes a coil
member 212 disposed therein. Coil member 212 is a substantially resilient
member that is biased to return to a resting position under a bending
load. Coil member 212 is fixedly disposed within outer tube 202 and may
be attached to the inner surface 202b of outer tube 202 in any suitable
manner, e.g., adhesion brazing or welding. Coil member 212 is disposed in
a helically wound configuration such that successive winds of coil member
212 define longitudinal spaces "S" between adjacent winds of the coil
member 212. Coil member 212 defines a second passageway 214.

[0045] In one embodiment, end effector 200 may also include an inner tube
216 rotatably disposed within coil 212. Inner tube 216 defines a third
passageway 218 therethrough, and includes a proximal end portion 220 and
a splined distal end portion 222. Proximal end portion 220 of inner tube
216 is configured and dimensioned to releasably connect to endoscopic
assembly 130. Splined distal end portion 222 of inner tube 216 is
slotted, defining a pair of tines 224a and 224b and a pair of channels
226a and 226b.

[0046] The plurality of fasteners 10 may be loaded into end effector 200
in any suitable manner. Though not shown in the figures, in one
embodiment, the plurality of fasteners 10 may be loaded directly into the
second passageway 214 of coil member 212. Coil member 212 has a
configuration such that opposing threaded portions 12a, 12b extending
from a head 12 of fastener 10 may be disposed within the longitudinal
spaces "S" between adjacent winds of coil member 212.

[0047] In another embodiment, as shown in FIG. 2B, splined distal end
portion 222 of inner tube 216 is capable of accepting the plurality of
fasteners 10 within third passage 218. In particular, the plurality of
fasteners 10 may be loaded into end effector 200 such that the pair of
opposing threaded sections 12a, 12b of fastener 10 extends through
respective channels 226a and 226b of inner tube 216 and are slidably
disposed within the longitudinal spaces "S" between adjacent winds of
coil member 212. Each fastener 10 is loaded into end effector 200 such
that adjacent fasteners 10 are not in contact with one another so as to
not damage distal tip 14 of each fastener 10.

[0048] Engagement member 300 is loaded into end effector 200 and is
disposed proximal to the plurality of fasteners 10. In one embodiment not
shown in the figures, engagement member 300 may be loaded directly into
the second passageway 214 of coil member 212. In this embodiment,
opposing threaded portions 312a, 312b of engagement member 300 may be
disposed within the longitudinal spaces "S" between adjacent winds of
coil member 212. In another embodiment as shown in FIG. 2B, engagement
member 300 may be loaded into the third passageway 218 of inner tube 216
proximal to the plurality of fasteners 10.

[0049] Turning now to FIGS. 4-6, engagement member or lockout member 300
according to an embodiment of the present disclosure is shown. Engagement
member 300 includes a body 310 having a substantially flat, disc-like
profile that has a proximal surface 310a and a distal surface 310b. As
briefly noted above, engagement member 300 includes two opposing threaded
portions 312a and 312b. Opposing threaded portions 312a and 312b protrude
radially outwardly from body 310 and are configured for engagement with
channels 226a, 226b of inner tube 216 of end effector 200. A pair of
radial gaps 314a, 314b is defined between the opposing threaded portions
312a, 312b of body 310 of engagement member 300. It is contemplated that
body 310 of engagement member 300 is substantially similar in size and
configuration to head 12 of fastener 10 such that engagement member 300
can be loaded and advanced along end effector 200 similar to fastener 10.

[0050] In some embodiments, engagement member 300 may be brightly colored
so that it is clearly visible through viewing window 204 of end effector
200. For example, in embodiments, engagement member 300 may be colored
red, blue, green, yellow or the like.

[0051] With continued reference to FIGS. 4-6, engagement member 300
includes a biasing portion 316, having a pair of biasing arms 316a, 316b
located within the respective radial gaps 314a, 314b of body 310. Biasing
arms 316a, 316b are integrally formed with and extend from body 310 in a
cantilevered fashion. In some embodiments, biasing arms 316a, 316b may be
separable components that are attached to body 310 via, e.g., brazing,
welding, an integrally formed living hinge or the like. Each biasing arm
316a, 316b terminates in a respective enlarged head portion 317a, 317b.

[0052] Biasing arms 316a, 316b may have an arcuate profile, as shown, and
may lie substantially parallel to the proximal surface 310a of body 310.
Biasing arms 316a, 316b may be disposed at a longitudinal position
between the proximal surface 310a and the distal surface 310b of body
310. Biasing arms 316a, 316b are configured for pivotal movement with
respect to the body 310. Biasing arms 316a, 316b have a flexible and/or
resilient configuration, and accordingly may define a spring constant.
Biasing arms 316a, 316b are biased toward a radially-outward or
cantilevered configuration, as mentioned above. In this manner, biasing
arms 316a, 316b are configured to pivot, flex or swing, radially
outwardly with respect to body 310.

[0053] The movement of biasing arms 316a, 316b allows engagement member
300 to transition between a first configuration (FIG. 6), in which
biasing arms 316a, 316b are approximated radially-inwardly toward body
310, and a second configuration (FIGS. 5A and 5B), in which biasing arms
316a, 316b are disposed radially outwardly with respect to body 310. With
reference to FIG. 5B, biasing arms 316a, 316b may define a radius of
curvature "R1", "R2" that approximates a radius of curvature "R3", "R4"
defined by body 310 within the radial gaps 314a, 314b to accommodate
folding the biasing arms 316a, 316b into the respective radial gaps 314a,
314b.

[0054] With reference to FIGS. 2A, 2B, and 4-5B, relative dimensions of
end effector 200, engagement member 300, and fastener 10 will be
detailed. For example, it is contemplated that a width "Y" of head
portions 317a, 317b of biasing arms 316a, 316b is greater than a width
"Z" of viewing windows 204 so that head portions 317a, 317b of biasing
arms 316a, 316b do not lock out into viewing window 204 during actuation
of end effector 200. Similarly, a thickness "W" of head portions 317a,
317b of biasing arms 316a, 316b is smaller than a width "X" of opposing
lockout windows 210a, 210b such that the head portions 317a, 317b of
biasing arms 316a, 316b can spring outward and grasp or enter into the
opposing lockout windows 210a, 210b. However, the width "X" of opposing
lockout windows 210a, 210b is smaller than a thickness "V" (FIG. 4) of
opposing threaded portions 12a, 12b of fastener 10 so that the plurality
of fasteners 10 do not get caught in the opposing lockout windows 210a,
210b.

[0055] With reference to FIGS. 1-8, in operation, end effector 200 is
operatively connected to endoscopic assembly 130 such that inner tube 216
of end effector 200 is rotated due to an actuation of trigger 114. As
inner tube 216 is rotated about the longitudinal axis "A-A," with respect
to coil member 212, the pair of tines 224a, 224b of inner tube 216
transmit the rotation of the inner tube 216 to the plurality of fasteners
10 and to engagement member 300. As a result, the plurality of fasteners
10 and engagement member 300 advance distally.

[0056] In particular, because the opposing threaded portions 12a, 12b of
fastener 10 are threadably engaged with the longitudinal spaces "S"
defined by the coil member 212, rotation of the tines 224a and 224b of
inner tube 216 urges the opposing threaded portions 12a, 12b to rotate
within the coil member 212 about the longitudinal axis "A-A" (FIG. 1A).
This in turn causes distal advancement of the plurality of fasteners 10
through outer tube 202 of end effector 200 along a helical path defined
by coil member 212. As fastener 10 approaches the distal end of end
effector 200, a tissue snaring section 14 and a distal tip 16 of fastener
10 protrude from outer tube 202. Further engagement and rotation by the
tines 224a and 224b of inner tube 216 causes fastener 10 to penetrate and
advance through, e.g., mesh "M" and into tissue "T."

[0057] Due to the similar configuration between head 12 of fastener 10 and
engagement member 300, rotation of inner tube 216 to distally advance the
plurality of fasteners 10 also distally advances engagement member 300.
Accordingly, after one of the plurality of fasteners 10 penetrates and
advances into tissue "T," engagement member 300 has been advanced
distally to the next adjacent graduated cutout 204a, corresponding to the
number of fasteners 10 still remaining within end effector 200.

[0058] It is contemplated that the location of the opposing lockout
windows 210a, 210b on outer tube 202 is such that, upon firing the last
fastener 10, engagement member 300 is distally advanced to, and aligned
with, the opposing lockout windows 210a, 210b of outer tube 202. Because
the thickness "W" of the head portions 317a, 317b of biasing arms 316a,
316b is smaller than the width "X" of each opposing lockout window 210a,
210b of outer tube 202, the axial and radial alignment between head
portions 317a, 317b of biasing arms 316a, 316b of engagement member 300
and the opposing lockout windows 210a, 210b allows for the biasing arms
316a, 316b to spring radially outward and for head portions 317a, 317b to
enter into a respective lockout window of opposing lockout windows 210a,
210b. At the same time, opposing threaded portions 312a, 312b of
engagement member 300 remain engaged with inner tube 216. As a result of
the engagement of head portions 317a, 317b of engagement member 300 in
lockout windows 210a, 210b of outer tube 202, and the engagement of tines
224a and 224b of inner tube 216 against threaded portions 312a, 312b of
engagement member 300, further rotation of inner tube 216 is mechanically
prevented. Therefore, end effector 200 is prevented from further
actuation. If additional fasteners 10 are required to complete the
surgical procedure, spent end effector 200 may be replaced with a new end
effector 200.

[0059] It will be understood that various modifications may be made to the
embodiments disclosed herein. Therefore, the above description should not
be construed as limiting, but merely as exemplifications of preferred
embodiments. Those skilled in the art will envision other modifications
within the scope and spirit of the claims appended thereto.